The object of the present invention is to provide a headlamp for vehicles by means of which the blinding or glaring phenomenon is eliminated, or is at least reduced to a large extent. To achieve such antiblinding effect, the headlamp of the invention comprises two reflecting surfaces which are joined to each other, between which a short straight filament is horizontally and parallely placed with respect to the main reflecting surfaces. The headlamp is completed by a converging lens output glass.
The two reflecting surfaces are semi-parabolas formed by displacing a parabola along a straight line. Such parabolas, which give rise to both the upper and lower reflecting surfaces forming the headlamp assembly, have different parabolic values.
The side parts of the headlamp are flat reflecting surfaces.
It should be pointed out that the upper part of the reflector, as well as the lower part thereof, when formed by parabolas which differ from each other, will give rise to the fact that the focal axes of such parabolas will not coincide, the axis of the lower part of the reflector being in an advanced position with respect to the focal axis of the upper part of the reflector. A lamp is connected to this structure, which lamp is cylindrical in shape and is placed parallely with respect to the headlamp, so that the filament of the lamp will be placed along the focal axis of the upper reflector.
The output glass, which all headlamps include, is in the case of a headlamp made according to the invention, a converging lens whose task is to corradiate the rays dispersed from the reflector and the filament, thus causing the rays to be deviated in a suitable manner so that the light beam, which emerges from such glass, is formed by approximately parallel rays.
With the structure which has just been explained, the light of the headlamps of a vehicle can be projected with a defined separation between a zone situated above a horizontal plane corresponding to the height of the headlamp, and an illuminated zone which will be precisely below such plane.
The upper reflector is a surface which emits light having a large divergence in a horizontal direction (just as in the case of the lower reflector) and a small divergence in a vertical direction, smaller than that of the lower reflector. The present invention is primarily concerned with vertical divergence.
Taking this divergence into account and supposing that the focal plane of the headlamp is horizontal (the plane which embraces the two focal axes, the filament and the vertex), then the luminous rays which emerge from the upper reflector are ascending, and they are more ascending, as they approach the edge i.e. as they are reflected more towards the upper end.
To prevent the luminous rays which emerge from the upper reflector from ascending, such reflector should be turned until its more ascending rays are situated in a horizontal position. The mode of carrying this out will be described subsequently. However, it is now necessary to clarify certain aspects of the invention which are also related to the turning of the upper reflector.
The first aspect refers to a manufacturing characteristic of the headlamp, according to which the illuminating zones of the upper reflector and those of the lower reflector are completely independent i.e. there is at no time any intersection of their rays. Consequently, this causes a weakening in the centre of the complete illuminating beam, precisely in the zone which separates the two illuminating zones of the two reflectors, due to the following reasons:
a. Tapering of the reflector in its assembly which is at its maximum in this zone. Thus, a reduction in the reflection capacity is produced. PA1 b. Presence of the bulb, with the corresponding appearance of reflections in the glass and distortion produced thereby. PA1 c. Presence of the opaque covering, with the corresponding shade production.
The second aspect is directly related to the secondary reflection which is produced in the interior of the headlamp, primarily due to the reflection of the light on the inner surface of the outlet glass. To prevent this reflection, which is a highly important factor in the blinding or glaring phenomenon and which makes the reflecting surfaces shine, there should be arranged in the interior of the headlamp a flat plate, both surfaces of which are covered with a non-reflecting substance or a light absorbing substance. This plate extends from one side of the headlamp to the other and from the proximities of the lens, until it touches the glass of the lamp. It will, at the same time, serve as a protecting cover which prevents direct ascending rays from being emitted.
With these two clarifications in mind, the manner in which the upper reflector should be turned so that the more ascending rays emerging therefrom are finally in a horizontal position and the illuminating zones of the upper and lower reflectors are at the same time joined, thus eliminating the weak zone, will now be described.
The turning of the upper reflector is effected for the filament, as an axis and from there the upper reflector is for the filament, as the axis and from there it is slightly turned until the previously mentioned plate is so positioned that it follows the direction of its rays without intercepting them. Once this has been achieved, the upper reflector is fixed in the assembly of the headlamp. Naturally, with this turning there is a zone which separates the vertices of the upper and lower reflecting surfaces, which before the turning, were coincident. However, due to the smallness of such zone with relation to the assembly of the reflector, its shape is of no great importance, hence it can be an accomodation surface between the two reflectors.
So-called levelling of the maximum ascending rays, which emerge from the upper reflector should be achieved with this turning. This is just as important as is the elimination of the possible weak zone which is formed around the focal plane. However, if the previously described turning is not sufficient to achieve the horizontal positioning of the maximum ascending rays of the upper reflector, a turning of the complete headlamp can be made until the desired positioning is achieved. Logically, this latter will depend on the divergence given to the upper reflector and to the inclination of the opaque-absorbing plate, which factors can be modified as desired.
To establish the position of the absorbing plate within the headlamp, the end thereof near to the lens is situated in the focal plane (horizontal) and the opposite end thereof is parallel to the focal axes and therefore, also horizontal, although slightly raised, with respect to the focal plane of the lower reflector.
When a headlamp assembly, made according to the invention is installed in a conventional automobile, safety or security in night driving is, increased, since blinding of the driver of a vehicle which travels in the opposite direction will be avoided or will be reduced to a great extent. This is another practical advantage of the invention i.e. the; elimination of the device for changing the bright and driving lights which is at present necessary in all vehicles.
Therefore, an object of the present invention is to provide a headlamp for vehicles which projects the light in such a way that there is a darkened zone above a horizontal plane situated at the height of the headlamps of the vehicle. Such zone protects the driver of an on-coming vehicle to which the headlamps of the invention have been adapted, while below such horizontal plane the contemplated headlamp illuminates the ground as well as the objects which are found in the zone below the height of the horizontal plane and the height of the headlamps.
With the headlamps which are presently used, it is not possible to achieve such separation of the illuminating zone and the darkened zone below and above the horizontal plane, respectively. This is due to the fact that the reflecting surface of a conventional headlamp is a revolution paraboloid which projects light, according to a diverging cone, both in a horizontal as well as a vertical direction and which therefore, emits light above the horizontal plane which establishes the position of the headlamps of the vehicle in question.